[improvement] Uploader: support preview network image (#3899)

src/uploader/utils.ts

@@ -26,6 +26,30 @@ export function isOversize(files: File | File[], maxSize: number): boolean {
   return toArray(files).some(file => file.size > maxSize);
 }
 
-export function isImageDataUrl(dataUrl: string): boolean {
-  return dataUrl.indexOf('data:image') === 0;
+export type FileListItem = {
+  url?: string;
+  file?: File;
+  content?: string; // dataUrl
+};
+
+const IMAGE_EXT = ['jpeg', 'jpg', 'gif', 'png', 'svg'];
+
+export function isImageUrl(url: string): boolean {
+  return IMAGE_EXT.some(ext => url.indexOf(`.${ext}`) !== -1);
+}
+
+export function isImageFile(item: FileListItem): boolean {
+  if (item.file && item.file.type) {
+    return item.file.type.indexOf('image') === 0;
+  }
+
+  if (item.url) {
+    return isImageUrl(item.url);
+  }
+
+  if (item.content) {
+    return item.content.indexOf('data:image') === 0;
+  }
+
+  return false;
 }